RADIUS Protocol under RFC2865 is vulnerable to forgery attacks.

The RADIUS authentication protocol has a critical weakness that allows an attacker on the local network to forge fake authentication responses, potentially tricking systems into granting unauthorized access. This happens because the protocol uses MD5, an outdated encryption method that can be manipulated.

RADIUS (RFC 2865) is vulnerable to chosen-prefix collision attacks against the MD5-based Response Authenticator, enabling local attackers to forge Access-Accept, Access-Reject, or Access-Challenge packets. The attack requires network proximity to intercept and modify responses in transit, compromising authentication integrity and potentially allowing unauthorized access to protected resources.